5.2 Mass and The Mole Learning Goals … … determine the molar mass (M) of an atom or molecule … use the formula m = n x M to solve for an unknown value … answer two step problems involving two formulas

Molar Mass (M) – mass of 1 mole of substance (g/mol) State the molar mass of the following: (a) Copper ________________ (b) phosphorus ________________ (c) H2O ________________ (d) H2SO4 ________________ (e) Fe(NO3)3 ________________ 63.55 g/mol 30.97 g/mol 18.02 g/mol 2 x 1.01 + 16 98.09 g/mol 2 x 1.01 + 32.07 + 4 x 16 241.88 g/mol 55.85 + 3 x 14.01 + 9 x 16

𝑛= 𝑚 𝑀 FORMULA: m = mass (g) n = number of moles (mol) M = Molar Mass (g/mol) 𝑛= 𝑚 𝑀 m n N atoms

Ex. Calculate the number of moles of 29.0 g of NaCl m = 29.0 g M = 58.44 g/mol n = ? mol n = m ÷ M = (29.0 g) ÷ (58.44 g/mol) = 0.496 mol  There are 0.496 mol of NaCl. m  n

Ex. Calculate the mass of 8.61x1021 molecules of KOH. m  n  N N = 8.61x1021 molecules M = 56.11 g/mol m = ? n = N / NA n = (8.61x1021 molecules)/(6.02 x 1023 molecules/mol) = 0.01430 mol m = n x M = (0.01430 mol)(56.11 g/mol) = 0.802 g  The mass of KOH is 0.802 g.

Ex. How many chlorine atoms are in 320.0 g of Iron (III)chloride? FeCl3 m = 320.0 g atoms = ? M = 162.2 g/mol n = m / M = (320.0 g) / (162.2 g/mol) = 1.9729 mol N = n x NA N = (1.9729 mol)(6.02 x 1023 molecules/mol) = 1.1877 x 1024 molecules # atoms = N x 3 Cl atoms/molecule = 3.563 x 1024 Cl atoms  There are 3.563 x 1024 Cl atoms in 320.0 g of FeCl3 m  n  N  atoms 3 Cl atoms

HOMEWORK p235 #36-39 p237 #46-49 p239 #56-59 p242 #61,62 CAN I … … determine the molar mass (M) of an atom or molecule … use the formula m = n x M to solve for an unknown value … answer two step problems involving two formulas HOMEWORK p235 #36-39 p237 #46-49 p239 #56-59 p242 #61,62